The admiral's comments Sunday indicated the loss of life could have been much worse.

"There was a big puncture, a big gash underneath the waterline" along the bottom of the ship, Aucoin said.

The water flow into compartments that were berthing areas for 116 of the ship's crew was "tremendous", he said, adding that "there wasn't a lot of time in those spaces that were open to the sea."

Aucoin said the cabin of the Fitzgerald's captain, Cmdr. Bryce Benson, was completely destroyed. "He's lucky to be alive," he added.

Benson was flown off the crippled ship by helicopter after the accident and was being treated at the naval hospital at Yokosuka, according to Aucoin, as were two other sailors who were medevaced.

Crew saved ship from sinking

The admiral said the ship had been in danger of sinking but was saved by the "heroic efforts" of the crew.

"The crew had to fight very hard to keep the ship afloat," he said.

The 10,000-ton guided-missile destroyer and the ACX Crystal, a 29,000-ton container ship flagged in the Philippines, collided early Saturday local time off Japan's Izu Peninsula, officials said. The area sees heavy maritime traffic, with 400 to 500 vessels crossing it daily.

The destroyer suffered severe damage to its starboard side, while the container ship sustained light damage.

A 7th Fleet statement said the collision did "significant damage and associated flooding to two berthing spaces, a machinery space, and the radio room."

Container ships like the Crystal have bulbous bows under the waterline and that portion of the cargo vessel plowed into the US warship.

The Fitzgerald had left the base Friday for routine operations.

Multiple investigations expected

Aucoin would not speculate on how the accident occurred, but said there would be multiple investigations into the collision, including one by the Navy's Judge Advocate General and one by the US Coast Guard.

Other investigations could come from the Japanese and Philippine authorities because of where the accident took place and the Philippine registry of the container ship.

The Fitzgerald is an Arleigh Burke-class guided-missile destroyer commissioned in 1995. The vessel is 505 feet long. It normally carries a crew of about 330 sailors and is homeported in Yokosuka.

Despite the significant damage to the destroyer, Aucoin said he expected it would rejoin the fleet.

"The ship is salvageable," he said. "It will take months, hopefully under a year" for repairs.

"You will see the USS Fitzgerald back as one of our warships," Aucoin said.

No one hurt on merchant ship

The ACX Crystal container ship is chartered by Japanese shipping company Nippon Yusen Kabushiki Kaisha (NYK) and owned by Dainichi-Invest Corporation, NYK said.

No one aboard the Crystal was hurt, and no oil spilled from the vessel, NYK said. It was back in port Sunday.

NYK and the ship's owner are cooperating with a Japan coast guard investigation into the collision, the shipping firm said.

"Our thoughts and deep concerns go out to all those directly affected," NYK said.

Photos of the Crystal showed damage to its bow.

The ship, which handles general cargo, is manned by a captain and a crew of 20, NYK said. It was built in 2008 and is about 730 feet long.